Spread of Muscle Spasms in Hemifacial Spasm.

Hemifacial spasm (HFS) is a clinical condition characterized by involuntary contractions in facial muscles. The aim of the study was to investigate, systematically in 178 patients with HFS, the frequency of spread from the site of origin to other facial muscles. Patients enrolled underwent a complete neurological examination and a face-to-face interview. Spread of the spasm to other facial muscles was considered to be present in those patients whose spasms onset in a single site and involved both upper and lower facial muscles at the time of examination. We also collected information about gender, age, age at HFS onset, symptom duration, muscles involved by the spasm at the time of onset, and spread of spasm to other facial muscles. Spread of spasms to the other facial muscles of the same side of the face was present in 93.4% of patients with HFS, and latency of spread was related to disease duration and age at onset. In patients with HFS, spread of muscle spasms represents the natural history of HFS.